Bisphosphonate-related femoral periosteal stress reactions: scoring system based on radiographic and MRI findings.

OBJECTIVE

The purpose of this study was to review the radiographic and MRI findings of bisphosphonate-related femoral periosteal stress reactions to propose a scoring system for predicting symptoms and fracture risk.

MATERIALS AND METHODS

A retrospective study included patients undergoing long-term bisphosphonate therapy who had radiographic evidence of focal femoral periosteal thickening on radiographs and MR images. There were 43 femoral periosteal stress reactions in 33 patients; eight patients underwent MRI. Radiographs and MR images were evaluated for focal cortical thickening (periosteal and endosteal), bone edema, focal cortical abnormalities (radiolucency, striations, cavities), and dreaded black line. The radiographic score (derived with statistical methods) and simple scores (simple radiographic, MRI, and combined scores) were compared with symptoms and fracture outcome.

RESULTS

Logistic regression analysis showed an association between radiographic dreaded black line and symptoms (odds ratio, 68.0). Kaplan-Meier and Cox regression analyses showed radiographic dreaded black line (p < 0.0005; hazard ratio, 27.3) and focal cortical radiolucency (p = 0.011; hazard ratio, 6.8) were independent predictors of fracture. The survival score derived from Cox regression coefficients showed good separation of high- and low-risk groups. Mann-Whitney tests showed an association between MRI and combined scores and symptoms (p = 0.036, p = 0.036). The area under the receiver operating characteristic curve suggested better association with symptoms for MRI and combined scores than for simple radiographic scores (1.00, 1.00, 0.93).

CONCLUSION

In bisphosphonate-related femoral periosteal stress reactions, radiographic dreaded black line and MRI and combined scores were associated with symptoms, and radiographic survival score was predictive of fracture risk. The relation between MRI and combined scores and fracture was not statistically significant.